The present invention is more particularly concerned with the cover assembly formed by the cover member of the diaphragm clutch and the diaphragm spring borne thereby, irrespective of whether the pressure plate has already been secured thereto, yet it is also concerned with the entire diaphragm spring clutch as well irrespective of the fact that the cover assembly is or is not assembled as an entirety or as components beforehand.
In such diaphragm spring clutches it is necessary to properly center the diaphragm spring with respect to the axis of the clutch or cover assembly.
To this end it is common to make use of assembly means which rockably mount the diaphragm spring on the cover member.
Indeed, the assembly means, whether they are in the form of individual posts or in the form of an annular clip ring or even if they are integrally formed with the cover member itself, all comprise, in succession, an anchoring portion by which they bear on the cover member, an axial portion passing through passages defined by spaces between consecutive radial fingers of the diaphragm spring at the radially inner, junction zone thereof, and an end portion located beyond the diaphragm spring by which they bear on the side of the diaphragm spring remote from the cover member, either directly or indirectly by means of two ring members one of which may be integrally formed with the cover member being provided between the cover member and the side of the diaphragm spring facing the same.
In passing through the diaphragm spring the assembly means usually bear against the edges defining the passages so as to insure centering.
But when the friction clutch is in operation, under the resilient force developed by the diaphragm spring axially against the cover member, the cover member is inevitably subjected to bending forces in the zone bearing the diaphragm spring which is precisely where the assembly means for rockably mounting the diaphragm spring to the cover member are situated.
Consequently the axial portions of the assembly means, particularly their end portions, are in the course of operation subjected to "coning" movements which are less controlled because, for the convenience of mounting, the assembly means are merely received in openings in the cover member at their anchoring portion, without being rigidly secured thereto.
Coupled with these coning movements of the assembly means are shifting movements due to acyclic movements emanating from the motor with which the cluch is associated.
The result of these different movements is not only premature wear of the parts involved, but also an uncentering of the diaphragm which causes it to operate under adverse conditions and has an unbalancing effect on the assembly means which secure the diaphragm spring to the cover member for rocking movement thereby augmenting the fatigue of these parts.
It has, of course been proposed, in order to eliminate the play of the assembly means securing the diaphragm spring to the cover member for rocking mounting to rigidly secure the assembly means to the cover member and thereby provide permanent centering of the diaphragm spring.
But experience has shown that unless the assembly means are of appreciable mass which for practical reasons is prohibitive, they are incapable of withstanding the stressing they are subjected to, owing to the different forces exerted thereon as briefly described above, and they yield or break when they serve to secure both the ring member between the cover member and the assembly means for the diaphragm spring on the side of the diaphragm spring opposite the cover member.